This invention generally relates to a method and apparatus that can be employed for ultrasonic processing operations. In particular features, the method and apparatus can include a rotary ultrasonic horn, and the ultrasonic processing can include an ultrasonic bonding operation. More particularly, the invention relates to an ultrasonic processing method and apparatus which can provide for an operative isolation of the rotary horn while employing a connection system that has relatively high rigidity and stiffness.
Conventional ultrasonic systems have included a rotary horn which cooperates with a rotary anvil. The conventional rotary ultrasonic horns have been supported and mounted by employing rubber or other elastomeric components to provide ultrasonic isolation. As a result, the ultrasonic horn has exhibited low static stiffness, low dynamic stiffness, and has exhibited excessively large amounts of run-out or other displacements during ordinary operation. Additionally, the conventional ultrasonic horn systems have employed complicated and unreliable torque transmission techniques.
Such conventional ultrasonic bonding systems have employed hydraulic or pneumatic devices to adjust a selected contact point at the work area in the nip region between the rotary horn and rotary anvil. Adjustable bevel blocks and adjustable screw stops have been employed to set the nip pressure and nip alignment. The adjustment systems have typically employed a xe2x80x9chard-stopxe2x80x9d to establish the control at the contact point in the nip region. The adjustment systems have been inefficient to operate, and have not provided an adequate mechanism for making sufficiently accurate adjustments. Additionally, the resulting ultrasonic bonding systems have been inadequate for operations which employ a desired, fixed-gap between a rotary horn and a rotary anvil, and have been inadequate for operations which employ a desired, intermittent bonding.
To help address the various shortcomings, the conventional ultrasonic bonding systems have employed additional support wheels to help maintain the ultrasonic horn in a desired position relative to the cooperating rotary anvil. Typically, the support wheels have been configured to hold the rotary horn in a substantially continuous, direct contact with the rotary anvil during ordinary operation. The use of such support wheels, however, has excessively increased the audible noise from the system, and has caused excessive wear on the working surface of the ultrasonic horn. Additionally, the horn has exhibited uneven wear, or has required the use of an oscillation mechanism to more evenly distribute the wear. Torque transmission systems needed for driving the rotary horn have been excessively costly, have required excessive maintenance, and have been difficult to setup and adjust. The conventional ultrasonic horn systems have also created areas on the working surface of the horn that have been unsuitable for performing desired bonding operations, and have not provided sufficient levels of dynamic stability. Additionally, the conventional ultrasonic bonding systems have required excessively critical adjustments, and have exhibited excessive complexity and excessive costs. Where rubber or other elastic materials are employed to provide acoustic isolation mounts, the mounts can generate excessive reflected energy if the elastomeric material is over compressed. As a result, there has been a continued need for improved ultrasonic bonding systems.
An ultrasonic processing method and apparatus can include a rotatable, ultrasonic horn member that is operatively joined to an isolation member which has high rigidity. A rotatable anvil member can be cooperatively positioned to provide a selected horn-anvil gap, and an automated drive can be connected to an actuator, or other transfer device, to automatically adjust the horn-anvil gap. An electronic processor can be configured to monitor an intermittent gap force detected from an output provided by a force sensor, and can provide a drive signal to the automated drive to thereby adjust the horn-anvil gap to operatively maintain a target, gap force value.
In a particular feature, the processing method and apparatus can include a rotatable ultrasonic horn member operatively joined to a first isolation member, and a second isolation member. In a further feature, the first isolation member can be capable of bending under a horn-life range of sonic frequencies to provide an operative component of motion along its radial direction and an operative component of motion along its axial direction. In other features, the second isolation member can exhibit high rigidity, and the second isolation member can be capable of bending under the horn-life range of sonic frequencies to provide an operative component of motion along its radial direction, and an operative component of motion along its axial direction.
In a particular aspect, each isolation member can have a radial isolation component and an axial isolation component. Each radial isolation component can be operatively joined to a corresponding axle member, and can be configured to extend at least radially from its corresponding axle member. The radial isolation component can be configured to operatively bend under the horn-life range of sonic frequencies. Each axial isolation component can be operatively joined to an operative portion of a corresponding radial isolation component, and can be configured to extend at least axially from its corresponding radial isolation component. The axial isolation component can be configured to operatively bend under the horn-life range of sonic frequencies.
The various aspects, features and configurations of the method and apparatus of the invention can provide a distinctive, rotary ultrasonic horn system which includes a corresponding wave-guide and at least one isolation member which has high rigidity and stiffness. The isolation member can operably isolate the radial motion that can arise at the longitudinal node of a wave-guide, and can provide sufficient bandwidth to compensate for nodal shifts that can occur during ordinary operation. The isolation member can also provide improved stiffness to reduce deflections under load. The increased stiffness can help maintain concentricity, and help to reduce run-out displacements. Additionally, the isolation member can more efficiently transmit torque and can provide improved effectiveness and efficiency. The isolation member can also be configured to reduce stress concentrations and to increase fatigue resistance, and can provide for a mounting system that can reduce relative motions between component parts. The method and apparatus of the invention can reduce the need for elastomeric isolation components, and can eliminate the need for conventional elastomeric O-rings and associated isolation-ring hardware. The method and apparatus can also reduce the need for torque transmission keys, and can avoid the use of auxiliary support wheels for maintaining the desired locations of the rotary horn and rotary anvil.
Additionally, the adjustment system can be configured to more effectively modify the nip region or other ultrasonic processing zone between the rotary horn and rotary anvil. Particular arrangements can provide an adjustment can allow a more efficient and more accurate adjustment of a nip gap region between the horn and anvil. The adjustment system can be further configured to provide an active regulation of the nip region, and the regulation can be provided during the operation of the method and apparatus. The adjustment system of the method and apparatus can be provided in a continual manner, and the regulation of the nip gap region can be conducted without the use of a hard-stop component. Additionally, the ability to selectively modify the nip gap can help compensate for changes in the method and apparatus that can occur during the processing operation. Such changes can be cause by mechanical wear, temperature variations, variations in the work material being bonded, and the like. The ultrasonic processing configurations provided by the method and apparatus of the present invention can also advantageously accommodate operations which employ a desired, fixed-gap between a rotary horn and a rotary anvil. The ultrasonic processing configurations can further provide a controlled regulation of a selected processing force, and an automatic adjustment of a processing gap region. In addition, the ultrasonic processing configurations provided by the present invention can also provide improved performance when conducting a desired, intermittent processing operation, such as intermittent bonding.